1. Field of the Invention
The present invention relates to a plasma treatment apparatus, and more particularly, to a plasma treatment apparatus capable of supplying pressure gas while preventing flying of particles accumulated on the bottom of a chamber.
2. Description of the Related Art
A conventional plasma treatment apparatus such as an etching apparatus, an ion injection apparatus, a sputtering apparatus or a low pressure CVD apparatus creates the interior of a process chamber into a vacuum atmosphere and conducts predetermined plasma treatment to a subject to be treated. This process camber is kept at a vacuum state when the process is performed, but should be changed to an atmospheric state and then opened when performing maintenance works. Thus, the process chamber includes an exhaust portion for exhausting the process chamber, and an intake portion for supplying pressure gas such as nitrogen into the process chamber to return the interior of the chamber to an atmospheric pressure.
Furthermore, once the interior of the process chamber is returned to the atmospheric pressure to take a subject to be treated into or out of the process chamber, the interior should be exhausted to a predetermined vacuum level for the next process, whereby it takes considerable time to perform the exhaust process.
Therefore, a load lock chamber with a small volume as compared with the process chamber is generally provided. In this case, since only the load lock chamber can be changed to an atmospheric pressure or a vacuum state, the yield of this process can be enhanced.
Accordingly, the load lock chamber should be repeatedly changed to atmospheric and vacuum environments as the subject to be treated is taken into and out of the chamber. To this end, the load lock chamber includes an exhaust portion for exhausting the interior of the chamber and an intake portion for supplying pressure gas therein.
However, reaction products generated during the plasma treatment and particles generated from a carrying or driving device generally remain within the process chamber or load lock chamber (hereinafter, referred to as ‘chamber’). The particles are accumulated on the bottom of the chamber over time.
Therefore, air flow created while supplying the chamber with pressure gas to return the interior to an atmospheric pressure blows off particles accumulated in the chamber, and then, the blown particles may adhere to the subject.
In order to solve the aforementioned problem, a conventional technology has proposed an improved chamber 10 including an intake portion 20 installed through the bottom of the chamber and protruding to a certain height from the bottom of the chamber, as shown in FIG. 1. That is, an opening formed at an end of the intake portion 20 for discharging pressure gas is positioned higher than particles accumulated on the chamber bottom to prevent the particles from being blown off by the supplied pressure gas.
However, this improved conventional technology can prevent particles from being directly blown off by air flow of pressure gas during the intake process, but cannot yet prevent the particles from being flying due to viscous flow S caused when the pressure gas is supplied.
As shown in FIG. 2, the pressure gas is supplied into the chamber through the intake portion 20. At this time, viscous flow S is formed around the intake portion 20, and is simultaneously propagated along a chamber wall. It has been also determined that this viscous flow S causes particles accumulated on the chamber bottom to fly off. Further, the same phenomenon has occurred during the exhaust process.
Furthermore, the particles accumulated on the chamber bottom cannot be yet discharged.